Catalyst composition for ethylene oligomerization and the use thereof

Abstract

The present invention relates to a catalyst composition for ethylene oligomerization and the use thereof. Such catalyst composition includes chromium compound, ligand containing P and N, activator and accelerator; wherein the chromium compound is selected from the group consisting of acetyl acetone chromium, THF-chromium chloride and Cr(2-ethylhecanoate)3; general formula of the ligand containing P and N is shown as:in which R1, R2, R3 and R4 are phenyl, benzyl, or naphthyl. R5 is isopropyl, butyl, cyclopropyl, cyclopentyl, cyclohexyl or fluorenyl; the activatior is methyl aluminoxane, ethyl aluminoxane, propyl aluminoxane and / or butyl aluminoxane; the accelerator is selected from the group consisting of 1,1,2,2,-tetrachloroethane, 1,1,2,2-tetrabromoethane, 1,1,2,2-tetrafluoroethane, and compounds having a formula of X1R6X2, in which X1 and X2 are F, Cl, Br, I or alkoxyl, R6 is alkylene or arylene group; the molar ratio of chromium compound, ligand containing P and N, activator and accelerator is 1:0.5˜10:50˜3000:0.5˜10. After mixing the four components mentioned previously under nitrogen atmosphere for 10 minutes, they are incorporated to the reactor, or these four components are incorporated directly into the reactor. Then ethylene is introduced for oligomerization. Such catalyst can be used in producing 1-octene through ethylene oligomerization. It is advantageous in high catalysing activity, high 1-octene selectivity, etc. The catalytic activity is more than 1.0×106 g product·ma−1 Cr·h−1, the fraction of C8 linear α-olefin is more than 70% by mass.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a catalyst system, in particular to a catalyst composition for ethylene oligomerization and to the use thereof.BACKGROUND OF THE INVENTION[0002]As it is known that linear α-olefins, such as 1-octene, 1-hexene, etc, are important chemical products and intermediates, they are widely applied in various fields such as comonomers of polyethylene, alcohols plasticizers, flavor additives, synthetic lubricant and additives of oil products. Employing 1-octene and 1-hexene as comonomers will significantly improve the density, and mechanical properties such as tear strength and tensile strength of polyethylene. When be used as alcohols to produce plasticizers, they could endue polyethylene articles better softness at low temperature, processing behavior, better outdoor weathering durability, particularly suitable for wires and cables, automobile accessories, decoration materials, etc.[0003]Even though 1-octene is of great importance ...

AI Technical Summary

Benefits of technology

[0013]The chief advantages and effects of the present invention lie in chromium-based catalyst of the invention because of the action of the accelerator, it is easily for four ethylene molecules to coordinate on four coordination bonds of chromium atom that are perpendicularly to each other. It is thus advantageous for self-polymerization of the four ethylene molecules to produce 1-octene selectively. Therefore, the catalyst has advantages of high activity, good selectivity to producing 1-octene and less by-product of polyethylene. The catalyst has activity of more than 1.0×106 g product·mol−1 Cr·h−1, while fraction of C8 linear α-alkene is more than 70% by mass.

Problems solved by technology

Even though 1-octene is of great importance in chemical industry, now there is no synthesis technique to produce 1-octene through ethylene oligomerization with high selectivity.

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